Matteo, along with his co-performer Carlo Aquino, had a special segment where they gave red roses to the crowd.
The 28-year-old actor-performer reserved the last rose for Sarah.
After singing his part of the song, Matteo approached his girlfriend, gave her the rose, and planted a soft kiss on her forehead.
He also gently stroked her chin and squeezed her wrist before heading back to stage.
Matteo and Sarah have been together for five years and celebrated their anniversary in Italy in September 2018.